2008 Kawasaki Jet Ski Ultra 250X Review

An ideal craft for going fast in any water condition

If your thing is going fast in a straight line – in any water condition – the Jet Ski Ultra 250X might be the boat for you.

Packing a legit 250 supercharged/intercooled horsepower under the seat, the Ultra 250X is good for zero-to-30 in less than two seconds and better than 65 mph with a full tank of fuel, and only goes faster as you burn off that load. Kawasaki says the hull is based on a championship-winning shape developed by its race teams, with a 22.5-degree, deep-vee profile that combines with this boat’s considerable weight to beat wind-blown chop into submission. Give this Ultra a heading, pull the throttle and it will track straight and true as a freight train on the express line. This explains why, after one year on the market, it’s become the boat of choice for endurance racers.

Charging at speed through the chop, the Ultra 250X is in its element.

Alas, eventually you’ll need to turn, and then things don’t go as well aboard the big Ultra, which is reluctant to change direction. Try to execute a high-speed sweeper, say rounding a point at 50 mph on smooth water, and you’ll fight a lot of nozzle pressure through the handlebars. On a buoy course, the Ultra is imprecise. It requires a lot of body positioning – try planting the outside foot and leaning off the seat to the inside – and then it tends to slide, rather than carve, through hard turns.

Like a train on rails, the Ultra 250X tracks straight and true at better than 65 mph.

I think these handling issues are the combined effect of this boat’s mass – it weighs 904 pounds dry, and well over 1,000 pounds fueled up and ready to ride – and that deep hull, which runs with a lot of keel in the water. This helps it track well and deliver a good ride in the rough stuff, but compromises handling.

The engine is a sweetheart, based on the 1.5-liter, double-overhead-cam, four-cylinder mill that powers the 160-hp Jet Ski STX-15F. It’s pumped up with a belt-driven Roots-type supercharger that pushes 11.4 psi through an air-to-water intercooler. High-flow fuel injectors, a larger 60mm throttle body, and a 4-2-1 exhaust system make good use of that positive pressure. The result is 250 peak hp at 8900 rpm and a mountain of torque at any engine speed above 5000 rpm when the blower kicks in.

The engine is also quite tractable, with good throttle control at towing speeds. I pulled a wakeskater with the Ultra and was able to get him on plane without even engaging the supercharger, so his arms remained attached to his body. The Ultra was then happy to chug along at 20 mph, its weight and deep hull providing outstanding stability against the tug of the boarder. This engine’s fault is its thirst. At 50 mph it’s burning 17 gallons per hour, and it requires premium gas. At the same speed, the Yamaha FX SHO burns just 10.4 gph.

The big, heavy Ultra is not very nimble. Note the amount of water being pushed by the bow as the boat plows through a turn. The Ultra carries its nose low and may simply punch through, rather than fly over, large boat wakes.

If the theme here is ‘big,’ the idea permeates every aspect of the Ultra. The 20.6-gallon fuel tank is the most generous on the market, as is the 58-gallon bow stowage compartment. It’s deep glove box will hold water bottles and sunscreen, and the seat is all-day comfortable but not too wide to straddle when standing. The handlebar angle is adjustable through five positions, and I appreciate that the reverse control is on the left side of the cowl, which lets the rider maintain throttle control while manipulating reverse in tight quarters. Following Jet Ski tradition, the seat comes off in two sections, but the aft stowage compartment is just a shallow tray on this boat, as the space below is occupied by the intercooler and large waterbox muffler.

Handlebars adjust to fit any rider, but the seat could use a little more bolster to hold the pilot in place on rough water.

I found the digital instrument display was difficult to read, and the small bar-graph fuel gauge was especially hard to see – and you need to keep an eye on the fuel gauge on this boat. The Ultra introduces a new micro-chip ‘key’ that activates the ignition when it’s inserted into a slot on the glove box. Unfortunately, you need to open the glove box door and depress the key every time the boat is restarted, which gets annoying. There’s a second Smart Learning Operation key that limits the engine to 5800 rpm and speed by 30 percent.

Instrument display is a mix of analog and digital. The fuel gauge, a narrow bar graph on the perimeter of the digital screen, is hard to read.

In its new Team Green and white livery, the Ultra 250X looks racy and sophisticated. Like all Kawasaki products, there’s a real feel of quality about the materials and fit-and-finish, a bonus considering its price is more than $1,000 less than the big-bore speed merchants from Yamaha and Sea-Doo. 

Classic Kawasaki green and white colors are new on the Jet Ski Ultra 250X for 2008. The muffler was also revised for quiet operation.

If you desire beat-thy-neighbor performance and spend a lot of time on rough water, the Ultra 250X will be a worthy partner.

Related Reading:
Kawasaki Ultra 250X handling kits
Kawasaki Ultra 250X with R&D kit